Electrophoretic display device and method for manufacturing same

ABSTRACT

A method of manufacturing is disclosed for an electrophoretic display apparatus that includes an array substrate and an electrophoretic film laminated to the array substrate. A thermally activated adhesive is used to adhesively attach the electrophoretic film to the array substrate. The electrophoretic film is first aligned to and flattened against the array substrate and then a substantially stronger than original adhesion property of the adhesive is activated by annealing at a high temperature that is substantially greater than room temperature. Rework prior to annealing is therefore possible when alignment errors occur between the electrophoretic film and the array substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2010-0025138 filed in the Korean IntellectualProperty Office on Mar. 22, 2010, the entire contents of whichapplication are incorporated herein by reference.

BACKGROUND

1. Field of Disclosure

The present disclosure of invention relates to electrophoretic displaysand methods of manufacturing the same. More particularly, the presentdisclosure relates to a method of binding together an electrophoreticfilm and an array substrate against which the electrophoretic film isflattened and aligned; with use of adhesive that is activated at hightemperature.

2. Description of Related Art

Generally, an electrophoretic display apparatus operates as a reflectivetype of display that selectively reflects light incident thereon andwhich is received from an external source where the selectivelyreflected light appears as an informational image to a user (viewer) ofthe display. More particularly, the electrophoretic display apparatus isgenerally structured to include a plurality of small microcapsules eachenclosing white ink particles pre-charged for example with a negativeelectric charge, black ink particles pre-charged with an opposedpositive electric charge, and a dielectric fluid where the microcapsuleis disposed between two electrodes, one of the electrodes often being alight-passing (e.g., transparent) electrode.

In the electrophoretic display apparatus, a voltage is applied and anelectric field is formed as between the opposed electrodes of arespective one or more microcapsules. In response to a first voltagepolarity and voltage magnitude, a white reflecting surface is caused tobe displayed when the white ink particles assemble adjacent to a viewingside of the light-passing microcapsule. By contrast and in response toan opposed second voltage polarity and sufficiently strong secondvoltage magnitude, a black color reflecting surface is caused to bedisplayed when the black ink particles exchange positions with the whiteparticles and come to be instead assembled adjacent to a viewing side ofthe microcapsule. Thus when a white light is incident from an externalsource onto differently driven microcapsules, the electrophoreticdisplay apparatus displays an image (e.g., black and white; or absorbingversus reflecting) corresponding to the white-light reflecting or blackand thus light-absorbing pixels defined by the respectively differentlydriven ones of the microcapsules.

One type of electrophoretic display apparatus is manufactured by bindingan electrophoretic microcapsules containing film to an array substrateon which a driving circuit integrally is formed. It is to be understoodthat this background of the technology section is intended to provideuseful background for understanding the here disclosed technology and assuch, the technology background section may include ideas, concepts orrecognitions that were not part of what was known or appreciated bythose skilled in the pertinent art prior to corresponding inventiondates of subject matter disclosed herein.

SUMMARY

A method of manufacturing an electrophoretic display in accordance withthe present disclosure includes: forming a monolithically integratedarray substrate including a plurality of thin film transistors (TFTs)with each being electrically connected to a corresponding gate line, acorresponding source line (data line), and a corresponding pixelelectrode; overlapping, flattening and aligning a flexibleelectrophoretic film having an electrophoretic layer against the arraysubstrate where the adhesive is interposed between the electrophoreticfilm and the array substrate; and annealing (curing) the adhesive at atemperature of more than about 60° C. but less than an adhesivedecomposing one (e.g., about 150° C.) for thereby providing asubstantial increase of adhesive strength to the adhesive after thepatterned electrophoretic film has been aligned to and flattened againstthe array substrate.

The adhesive may include at least two reactive compositions whose crossreaction is selectively induced by a temperature substantially aboveroom temperature, and the at least two compositions may include a phenolresin.

The at least two compositions may include an acrylic rubber.

The adhesive may include a silicon filler at over 0% and under 15% byweight composition ratio.

The adhesive may include an acrylic rubber at over 40% and under 80% byweight composition ratio.

The adhesive may include a phenol resin such as bisphenol A and an epoxyresin.

The adhesive may include an epoxy phenol resin at over 0% and under 50%by weight composition ratio, a silicon filler at over 0% and under 15%by weight composition ratio, and an acrylic rubber at over 40% and under80% by weight composition ratio.

An electrophoretic display in accordance with the present disclosureincludes: an array panel including a thin film transistor connected to agate wire and a source wire, and a pixel electrode connected to the thinfilm transistor; an electrophoretic film including a patternedelectrophoretic layer (e.g., one having a framing area that frames(surrounds) a display area thereof) and a common electrode; and anadhesive positioned between the electrophoretic film and the arraypanel, wherein the adhesive includes a phenolyic resin such as bisphenolA and an epoxy resin.

The adhesive may include an epoxy phenol resin made of an epoxy resinand a phenol and having an over 0% and under 50% weight compositionratio.

The adhesive may include a silicon filler at 0% and under 15% by weightcomposition ratio.

The adhesive may include an acrylic rubber at over 40% and under 80% byweight composition ratio. The manufactured electrophoretic display inaccordance with the present disclosure has the patterned electrophoreticlayer that may be pre-aligned to and flattened against a correspondingpattern (e.g., display area and peripheral area) on the array substrate,with the pre-aligned and flattened electrophoretic layer being stronglyadhered to the array panel by a temperature cured version of theadhesive.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present disclosure ofinvention will become more apparent by describing exemplary embodimentsthereof in detail with reference to the accompanying drawings, in which:

FIG. 1 is a plan view illustrating an electrophoretic display apparatusaccording to an example embodiment;

FIG. 2 is a cross-sectional view illustrating the electrophoreticdisplay apparatus according to a first example embodiment taken along aline I-I′ of FIG. 1;

FIGS. 3A and 3B are sectional views illustrating a method formanufacturing the electrophoretic display apparatus in FIG. 2;

FIG. 4A is a chemical formula of an exemplary adhesive composition of abisphenol A type;

FIG. 4B is a chemical formula of an exemplary adhesive composition epoxyresin;

FIG. 5 shows SEM and AFM pictures according to exemplary X1 and X2samples; and

FIG. 6 is a diagram of weight variation according to an increase oftemperature for exemplary X1, X2, and X3 samples.

DETAILED DESCRIPTION

The present teachings are described more fully hereinafter withreference to the accompanying drawings in which embodiments inaccordance with the disclosure are shown. These teachings may, however,be embodied in many different forms and should not be construed aslimited to the embodiments set forth herein. Rather, these embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the present teachings to those skilled inthe art. In the drawings, the size and relative sizes of layers andregions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to,” or “coupled to” another element or layer, itcan be directly on, connected to, or coupled to the other element orlayer or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directlyconnected to,” or “directly coupled to” another element or layer, thereare no intervening elements or layers present. Like numbers refer tolike elements throughout. As used herein, the term “and/or” includes anyand all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, components,regions, layers, and/or sections, these elements, components, regions,layers, and/or sections should not be limited by these terms. Theseterms are only used to distinguish one element, component, region,layer, or section from another region, layer, or section. Thus, a firstelement, component, region, layer, or section discussed below could betermed a second element, component, region, layer, or section withoutdeparting from the teachings of the present disclosure.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures.

It will be understood that the spatially relative terms are intended toencompass different orientations of the device in use or operation inaddition to the orientation depicted in the figures. For example, if thedevice in the figures is turned over, elements described as “below” or“beneath” other elements or features would then be oriented “above” theother elements or features. Thus, the term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein are to be interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure of invention. As used herein, the singular forms “a,” “an,”and “the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Exemplary embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of the invention. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments should not be construed as limited to theparticular shapes of regions illustrated herein but are to includedeviations in shapes that result, for example, from details ofmanufacturing. For example, an implanted region illustrated as arectangle will typically have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from an implanted to non-implanted region. Likewise, a buriedregion formed by implantation may result in some implantation in theregion between the buried region and the surface through which theimplantation takes place. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe actual shape of a region of a device and are not intended to limitthe scope of the present teachings.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure most closelypertains. It will be further understood that terms such as those definedin commonly used dictionaries should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand will not be interpreted in an idealized or overly formal senseunless expressly so defined herein.

Hereinafter, embodiments will be explained in detail with reference tothe accompanying drawings.

FIG. 1 is a plan view illustrating an electrophoretic display apparatusformed according to an example first embodiment of the presentteachings.

Referring to FIG. 1, the electrophoretic display apparatus includes anelectrophoretic display panel 300 and an electrical driving part 410structured and connected for driving the electrophoretic display panel300.

The electrophoretic display panel 300 includes an array substrate 100and an electrophoretic film 200, flattened against and adhesively bondedto the array substrate 100. The array substrate 100 is patterned toinclude a display area DA of predefined size and shape (e.g.,rectangular) and a peripheral area immediately surrounding the displayarea DA.

Individual pixel portions P are defined in the display area DA as areasbounded by source lines DL and gate lines GL, where the latter two arenonconnectively crossing each other. Each of the pixel portions Pincludes a thin film transistor TFT (only one shown) electricallyconnected to the gate and source lines, GL and DL, corresponding to eachpixel portion P. Each of the pixel portions P may be furtherschematically represented as having a corresponding electrophoreticcapacitor EPC electrically connected to the TFT, and a storage capacitorCST electrically connected, for example in parallel with the EPC.

The peripheral area includes a peripheral first outer area OA (alsoreferred to here as a picture framing area) disposed immediatelyadjacent to the display area DA and surrounding the display area DA likea picture frame, a first further peripheral area PA1 that corresponds toa portion where the source lines DL extending outside of the displayarea DA and where the driving part 410 is disposed to connect with them.The peripheral area also includes a second further peripheral area PA2corresponding to a portion where the gate lines GL extend outside of thedisplay area DA. The second further peripheral area PA2 includes acircuit area CA in which a gates-driving circuit part GIC is formed foroutputting corresponding gate signals to the gate lines GL. Thegates-driving circuit part GIC is monolithically integrated with thedisplay area DA elements (e.g., TFTs) to the substrate 300. As is thecase with the display area DA, the gates-driving circuit part GIC has apredefined shape and size and location relative to the display area DA,and in one embodiment, a correspondingly patterned portion of theelectrophoretic film 200 might desirably need to be aligned with thecircuit area CA.

More specifically, a light blocking electrode (not separately shown inFIG. 1) is formed in the peripheral area portion OA of the arraysubstrate 100, and a patterned light blocking layer covering the gatecircuit part GIC is further formed in the circuit area portion CA of thearray substrate 100. As a consequence, the electrophoretic film 200 hasto be properly aligned to the correspondingly patterned portions of theunderlying array substrate 100 so as to provide electrically activatedlight-blocking action as will be described below.

More specifically, during operation, a data voltage corresponding to ablack grayscale is applied to the light-blocking electrode of theelectrophoretic film 200, for thereby causing the portion of theelectrophoretic layer located there to display the black grayscale inthat area. Accordingly as the peripheral area OA (a.k.a. framing area)immediately adjacent to the display area DA is displayed in thecontrasting black grayscale, viewing ability of an image displayed inthe display area DA is relatively enhanced. The light-blocking layer ofthe electrophoretic film 200 blocks external light from being incidentto active electronic elements of the underlying gate circuit part GICformed in the circuit area CA, to thus prevent the gate circuit part GICfrom being erroneously operated.

The electrophoretic film 200 includes, at its user-viewed major surface,an integral common electrode formed of a light-passing (e.g.,transparent) and electrically conductive material. The transparentcommon electrode is formed on a supporting base substrate made of aflexible material. The electrophoretic film 200 further includes anelectrophoretic layer is formed on the common electrode. Theelectrophoretic layer includes electrophoretic molecules or particles(e.g., microcapsule encapsulated particles) charged with either apositive (+) charge and a negative (−) charge. The electrophoretic film200 is adhesively attached to a top major surface of the display area DAportion of the main array substrate 100, as well as to the secondperipheral area PA2, and the peripheral area OA of the array substrate100.

FIG. 2 is a cross-sectional view taken along a line I-I′ of FIG. 1 andillustrating the electrophoretic display apparatus according to a firstexample embodiment.

Referring to FIGS. 1 and 2, the electrophoretic display apparatusincludes the array substrate 100 and the electrophoretic film 200pre-aligned to, flattened against, and thereafter strongly adhesivelybonded to the array substrate 100. The array substrate 100 includes afirst base substrate 101, and the first base substrate 101 has thedisplay area DA, the peripheral area OA, and the circuit area CA definedon an upper major surface thereof.

A thin film transistor layer TL is formed in the display area DA. Thethin film transistor layer TL includes a plurality of thin filmtransistors (TFTs) each having a respective gate electrode GE, a portionof gate insulating layer 120, a channel portion CH, a respective sourceelectrode SE, a respective drain electrode DE, a portion of protectiveinsulating layer 150, a portion of first organic insulating layer 160,and a respective pixel electrode PE.

The gate electrode GE of each TFT is formed to be extended from acorresponding gate line GL, and the gate insulating layer 120 is formedon the gate line GL and on the gate electrode GE. The channel portion CHincludes an active layer 131 including an amorphous silicon (a-Si) and alow-resistance contact layer 132 including amorphous silicon (a-Si)doped with N-type dopants at a high concentration (n+ a-Si).

The source and drain electrodes SE and DE are formed on the channelportion CH, but separated from each other by a TFT channel area. Whenthe TFT is turned ON, the source and drain electrodes, SE and DE. of theTFT are effectively electrically connected with each other through amade-conductive portion of the channel portion CH. The source electrodeDE is formed to be extended from the source line DL, and the drainelectrode DE is electrically connected to the pixel electrode PE througha contact hole CT. Thus, the thin film transistor TFT having the gateelectrode GE, the channel portion CH, the source electrode SE and thedrain electrode DE is formed.

The protective insulating layer 150 and the first organic insulatinglayer 160 are formed one after the next in the recited order on top ofthe first base substrate 101 and on top of the thin film transistorsTFTs formed on the first base substrate 101. The protective insulatinglayer 150 and the first organic insulating layer 160 have the contacthole CT defined through them so that a portion of the drain electrode DEis exposed for connecting with the pixel-electrode PE. In oneembodiment, the first organic insulating layer 160 is composed of atransparent organic insulating material. The upper surface of the firstorganic insulating layer 160; as well as the upper surface of asoon-described, second organic insulating layer 180 has a compositionthat can strongly bind with a thermally activated adhesive layer 500provided between the bottom major surface of the electrophoretic film200 and the top major surface of the array substrate 100, where thelatter top surface of substrate 100 is defined by coplanar uppersurfaces of the first and second organic insulating layers, 160 and 180.The thermally activated adhesive layer 500 also binds well to theconductive material of electrodes 191 and 192 in the areas where thoseblack-grayscale inducing electrodes are formed.

The pixel electrode PE is formed on the first organic insulating layer160, to be electrically connected to the drain electrode DE through thecontact hole CT.

The gate insulating layer 120, the protective insulating layer 150, andthe first organic insulating layer 160 are sequentially formed on theperipheral area OA (a.k.a. framing area) as well. A light-blocking (andblack-grayscale inducing) electrode 191 made for example of an opaquemetal material is formed in the array substrate 100 to be disposeddirectly above the first organic insulating layer 160. During operation,a black grayscale voltage is applied through an appropriate connector tothe blocking electrode 191 to cause display thereat of the blackgrayscale as mentioned above.

The circuit area CA includes a gate circuit layer GCL electricallyconnected to the plurality of thin film transistors of the display areaDA, a second organic insulating layer 180, and a light-blocking layer192.

The gate circuit layer GCL includes a gate metal layer 110, the gateinsulating layer 120, the channel layer 130, a source metal layer 140,the protective insulating layer 150, and a contact electrode 172. In oneembodiment, the gate circuit layer GCL and the thin film transistorlayer TL are simultaneously formed via the same manufacturing process.The second organic insulating layer 180 may be composed of the sametransparent organic insulating material as used for the first organicinsulating layer 160.

The blocking layer 192 in the CA area of the array substrate 100 may becomposed of the same opaque metal material as used for the blockingelectrode 191 in the OA area (a.k.a. framing area). The blocking layer192 is formed to alignably cover the gate circuit layer GCL, to thusprevent light from being incident to the gate circuit layer GCL from anexternal source. Thus, leakage current is prevented from flowing due tolight striking light-sensitive active elements in the gate circuit partGIC. The second organic insulating layer 180 electrically insulates thecontact electrode 172 (which contact electrode 172 can extend to outsidethe second organic insulating layer 180) and the blocking layer 192. Thesecond organic insulating layer 180 helps to flatten (planarize) theupper surface of the array substrate 100 just as does the coplanar topof the first organic insulating layer 160 formed in the peripheral areaOA help to flatten (planarize) the upper surface of the array substrate100.

The electrophoretic film 200 includes a second base substrate 201, acommon electrode 210, and an electrophoretic microcapsules-containinglayer 240.

The second base substrate 201 may be made of a flexible material. Forexample, the second base substrate 201 may include a polyethyleneterephthalate (PET) having good light transmissivity, goodheat-resistance, good resistance to chemical attack, good mechanicalstrength, and so on.

The common electrode 210 includes a transparent conductive material. Thecommon electrode 210 is disposed opposite to pixel electrodes PE of thearray substrate 100 so as to thereby sandwich the microcapsules inbetween. A common voltage is applied to the common electrode 210. Thecommon electrode is composed of a transparent conductive material, suchas indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tinoxide (a-ITO), and so on. The pixel-electrodes PE need not belight-passing ones (since the display operates by reflection of incidentlight) but they nonetheless can be such and can be also composed of atransparent conductive material, such as indium tin oxide (ITO), indiumzinc oxide (IZO), amorphous indium tin oxide (a-ITO), and so on.Alternatively, the pixel-electrodes PE may be composed of an opaque andotherwise appropriate conductor.

The electrophoretic layer 240 includes a plurality of microcapsules 230and a flexible transparent binder (not referenced with a number) bindingthe plurality of microcapsules 230 together. Each of the microcapsules230 includes the electrophoretic molecules or particles charged with oneor the other of the positive (+) and negative (−) charges.

Particularly, in one embodiment, the microcapsules 230 include white inkparticles 231 charged with the negative (−) charge and the positive (+)charge, black ink particles 232 charged with the opposite charge to thewhite ink particles 231, and a transparent dielectric 233. Alternativelythe white ink particles 231 may be charged with the positive (+) chargeand the black ink particles 232 may be charged with the negative (−)charge. As shown in FIG. 2, if the white ink particles 231 arepositioned at the upper side, the light incident from the externalsource is reflected by the white ink particles 231 to thus display acorresponding white colored or white light-reflecting area.(User-observed color may vary if color filters of different colors,e.g., R, G, B are provided above the electrophoretic film 200.)

FIGS. 3A and 3B are sectional views illustrating a method formanufacturing the electrophoretic display apparatus of FIG. 2.

Referring to FIGS. 2 and 3A, the thin film transistor layer TL isintegrally formed on the first base substrate 101 in the display areaDA, and the gate circuit layer GCL is integrally formed in the circuitarea CA.

Particularly, a first metal layer is deposited and patterned on thefirst base substrate 101. Then, the gate electrode GE and the gate lineGL are formed in the display area DA, and the gate metal layer 110 isformed in the circuit area CA. The patterned gate metal layer 110includes the gate electrodes of the plurality of thin film transistorsforming the gate circuit part GIC.

The gate insulating layer 120 is formed on the first base substrate 101on which the gate pattern is formed. The gate insulating layer 120 isformed in the display area DA, the peripheral area OA, and the circuitarea CA in common.

The active layer 131 having amorphous silicon (a-Si) and thelow-resistance contact layer 132 having amorphous silicon doped withN-type dopants at a high concentration (n+ a-Si) are sequentiallydeposited and patterned on the gate insulating layer 120. Then, thechannel portion CH is formed in the display area DA, and the channellayer 130 is formed in the circuit area CA. The active layer 131 and thelow-resistance contact layer 132 are not formed in the peripheral areaOA.

A second metal layer is deposited and patterned on the first basesubstrate 101 on which the channel portion CH and the channel layer 130have been formed. Then, the source line DL, the source electrode SE, andthe drain electrode DE are formed in the display area DA, and the sourcemetal layer 140 is formed in the circuit area CA. The source metal layer140 includes the source and drain electrodes of the plurality of thinfilm transistors forming the gate circuit part GIC.

The protective insulating layer 150 is formed on the first basesubstrate 101 on which the source pattern is formed. The protectiveinsulating layer 150 is formed in the display area DA, the peripheralarea OA, and the circuit area CA in common.

Then, the first organic insulating layer 160 having the transparentorganic insulating material is formed in the display area DA and theperipheral area OA. However, the first organic insulating layer 160 isnot formed in the circuit area CA. The transparency of the first organicinsulating layer 160 may be used during manufacture to optically alignpatterned features below the first organic insulating layer 160 topatterned features of the electrophoretic film 200.

The first organic insulating layer 160 and the protective insulatinglayer 150 formed in the display area DA are patterned to form thecontact hole CT. The protective insulating layer 150 and the gateinsulating layer 120 formed in the circuit area CA are patterned to forma plurality of contact holes (not shown).

A conductive and optionally transparent electrode material is depositedand patterned on the first base substrate 101 on which the contact holesare formed, to thus form the pixel electrodes PE in the display area andto thus form a predefined pattern of contact electrodes 172 in thecircuit area CA (which area is not yet covered by the second organicinsulating layer 180). The contact electrodes 172 may extend beyond anarea to be next covered by the second organic insulating layer 180.

Accordingly, the thin film transistor layer TL is formed in the displayarea DA and the gate circuit layer GCL is formed in the circuit area CA.The gate insulating layer 120, the protective insulating layer 150, andthe first organic insulating layer 160 are sequentially formed in theperipheral area OA.

Referring to FIGS. 2 and 3B, the second organic insulating layer 180having the transparent organic insulating material is formed on thefirst base substrate 101 in the circuit area CA. The second organicinsulating layer 180 is formed to cover the contact electrodes 172. Thefirst and second organic insulating layers, 160 and 180 are thenplanarized together so that the second organic insulating layer 180planarizes its portion of the top surface of the array substrate 100just as does the first organic insulating layer 160 planarize itsrespective portion of the top surface of the array substrate 100.

An opaque metal material is next deposited and patterned on the secondorganic insulating layer 180, to form the light-blocking electrode 191in the peripheral area OA and to form the light-blocking layer 192 inthe circuit area CA. Black grayscale data is applied to the blockingelectrode 191 during operation so that the viewing ability of the imagedisplayed in the display area DA is enhanced. The blocking layer 192 isformed to cover the gate circuit layer GCL to block the light from beingincident to the gate circuit layer GCL.

The blocking electrode 191 and the blocking layer 192 are formed tocomplete the array substrate 100. The electrophoretic film 200 havingthe electrophoretic layer 240 is laminated, and more specifically,flattened against and thereafter adhesively attached to the arraysubstrate 100 by a below described bonding process. The electrophoreticfilm 200 is attached to cover the display area DA, the peripheral areaOA, and the circuit area CA of the array substrate 100.

A selectively activatable adhesive 500 is used when the electrophoreticfilm 200 is laminated (adhesively attached) to the array substrate 100.In one embodiment, an adhesive film having a thickness of about 25 um isinitially covered by protective films on both the front and rearsurfaces thereof. First, the front cover is removed and the partlyexposed adhesive film is laminated onto (e.g., flattened against so asto remove gas pockets and loosely held by electrostatic and/or alikeweak adhesion forces to) the electrophoretic film 200, and secondly, therear cover is removed and the so-exposed electrophoretic film 200 islaminated onto (e.g., flattened against so as to remove gas pockets andloosely held by electrostatic and/or alike weak adhesion forces to) thearray substrate 100. At the time of the second laminating, precisearrangement (alignment) between the electrophoretic film 200 and thearray substrate 100 may be required since the adhesive 500, after it isthermally activated, will be strong enough to damage the surface ofsubstrate if it is unintentionally contacted thereto in wrong alignmentand afterwards, detachment is attempted. The damage to theelectrophoretic film 200 or the array substrate 100 due improperlyaligned strong attachment is expensive since it is a half-finishedproduct and must be discarded if the bonding process is carried out withan acceptable flattening and/or alignment.

As taught by the exemplary embodiment of the present disclosure, thetrouble may be solved by using a selectively activatable adhesive 500that is selectively activated for example only at a temperaturesubstantially higher than room temperature. Detaching at roomtemperature is easy and free from damage to the surface of the substratesince it is not particularly adhesive at room temperature or below.Accordingly, after the temperature-based hardening process is applied,the electrophoretic film 200 and the array substrate 100 are stronglyadhered to each other by the cured adhesive layer 500. That is, theelectrophoretic film 200 and the array substrate 100 are first flattenedout against each other and appropriately aligned with each other at roomtemperature or a lower temperature, and they are fixed in positionrelative to one another and thereafter permanently adhered to oneanother by hardening the adhesive 500 at a high temperature such thatthey are attached without any substantial misalignment or air or othergas pockets interposed therebetween. Also, although both surfaces areloosely attached via the not-yet-cured adhesive when trying to align atroom temperature, detaching is easy prior to hardening such that damagedue to detachment and re-lamination may not be generated even if amisalignment and/or wrinkle-air pocket is generated during a firstlamination attempt.

Exemplary components of the adhesive composition 500 may include one ormore phenolyic resins with an OH functional group and an epoxy resinhaving an aromatic (e.g., benzene-based) component. One example of thephenolyic resins may be bisphenol A, and the corresponding compound maybe represented by the chemical formula of FIG. 4A. The structure of theepoxy resin is may be represented by the chemical formula of FIG. 4B. Atthe above room temperature range of about 50° C. ˜150° C., the OHfunctional group of the phenolyic resin (FIG. 4A) is believed tochemically combine (e.g., cross polymerize with) with the epoxy resin tothus form a web-shaped epoxy phenol resin. Additionally, the acrylicgroups of the acrylic rubber addend may attach at the sites indicated inFIGS. 4A-4B.

Thus, according to an exemplary embodiment, an adhesive is composed ofat least three components of an epoxy phenolyic resin complex of whichthe phenolyic resin and the epoxy resin are combined (cross polymerized)by thermal reaction at an activating temperature, where the adhesive mayadditionally include at least one of an acrylic rubber and a siliconfiller. Here, when included, the acrylic rubber preferably has arelatively low elasticity and thus contributes to relaxation of stress.Similarly, when included, the silicon filler is believed to contributeto improving cohesion within the adhesive film.

With an increase in proportion of epoxy content, the heat resistance(e.g., resistance to premature polymerization at lower temperatures) ofthe resulting adhesive material increases but its adhesion strengthdecreases and the amount of outgas increases. On the other hand, with anincrease in proportion of the acryl contents, its heat resistancedecreases. Since the silicon filler is agglomerated when the content ofthe silicon filler is increased, it is desirable to be controlled to beunder about 10 wt % with a 1 micron average particle size (e.g., averagediameter).

The statistically processed results of testing are shown in Table 1 withrespect to properties regarding transmission, detaching, and outgassing.In the experiments, a testing film is inserted between two pieces ofglass, light-transmission is measured after it is hardened at 150° C.with a light of a 440 nm wavelength, a T-peeling test is performed toestimate detachment for a rework, the angle between the detaching filmand the attached part is kept at 90° and the weight change with theincrease of temperature is measured to estimate the amount of outgas.

Formulation X1 in the given Table 1 is composed of 30 wt % of epoxyphenol resin, 60 wt % of acrylic rubber, and 10 wt % of silicon filler,and the average particle size of the epoxy hardener is 500 nm.Formulation X2 is composed of 10 wt % of epoxy phenol resin, 80 wt % ofacrylic rubber, and 10 wt % of silicon filler, and the average particlesize of the epoxy hardener is 100 nm. The third formulation, X3 iscomposed of 20 wt % of epoxy phenol resin, 70 wt % of acrylic rubber,and 10 wt % of silicon filler, and the average particle size of theepoxy hardener is about 10 nm.

TABLE 1 Items HS-300- HS-300- HS-300- 10-X1 10-X2 10-X3 Transpar-Transmittance at 400 nm 22 45 82 ency (%) (Foaming) Workabil- Tackinessat 40° C.(N) 0.11 2.3 0.35 ity Hand peeled GOOD BAD PASS T-peel PE cover0.6 27 0.7 strength film (N/m) PET base 1.7 2.2 0.3 film OutgasTemperature −1% 292 141 243 of mass change ratio (° C.) −3% 328 234 316−5% 339 276 336

In regards to properties of the outgas, a 1% weight loss in X1 and X3was observed at a higher temperatures as compared to the −1% losstemperature of X2. In the same way, 3% and 5% weight losses of X1 and X3were observed at higher temperatures as compared to the corresponding−3% and −5% loss temperatures of X2. In other words, thermal stabilityof X1 and X3 is better than that of X2 with regard to mass loss (e.g.,due to outgassing).

In regards to detachment of a film at room temperature, X1 and X3 arerelatively better than X2. From the test, required force to detach isminimal, at 0.3N/m in the combination of X3 and the PET base film.

The best performance in the light-transmission test was observed withX3.

In FIG. 5, surface SEM (scanning electron microscope) and AFM (atomicforce microscope) images in regards to X1 samples (left column) and X3samples (right column) are presented. Phase decomposition of acrylrubber and epoxy resin is well established in the X1 sample as seen inits AFM image.

In FIG. 6, weight change versus progressive increase of temperature inregards to X1, X2, and X3 samples is graphed. The superior thermalstability of the X1 composition (dashes only plot line) is shown as bestin the diagram relative to X2 (dash-dot plot line) and X3 (solid) byvirtue of the substantially more flat and low loss percent all the wayout to about 300° C. whereas X2 and X3 exhibit faster mass loss at lowertemperatures (although X3 is superior below about 250° C.).

Accordingly, if prevention of compositional change in the utilizedadhesive is desired up to as high as about 300° C. (see FIG. 6, X1 plot)and the higher surface roughness (see FIG. 5, left column side) of curedX1 is acceptable, then the X1 composition and its approximatingequivalents may be preferred. On the other hand, if a reduced surfaceroughness (see FIG. 5, right column side) in the utilized adhesive isdesired and a lesser selectivity in terms of activating temperature isacceptable, then the X3 composition and its approximating equivalentsmay be preferred.

1. A method of manufacturing an electrophoretic display, comprising:forming a display array substrate including a thin film transistormonolithically integrally formed thereon and electrically connected to agate line, a source line, and a pixel electrode also integrally formedon the array substrate; providing a selectively activatable adhesivewhich cures at a temperature substantially above room temperature;providing an electrophoretic film having the selectively activatableadhesive loosely adhered to a bottom major surface of theelectrophoretic film where the bottom major surface opposes a top majorsurface of the electrophoretic film from which top major surface, imagedefining light will be reflected to a viewing user of theelectrophoretic display; overlapping and aligning the combination of theelectrophoretic film and the selectively activatable adhesive on thearray substrate; and after alignment is complete, annealing the adhesiveby subjecting it to a temperature of more than 60° C. for therebysubstantially increasing adhesive strength of the adhesive relative toat least one of the adjacent array substrate and electrophoretic film.2. The method of manufacturing of claim 1, wherein the adhesive includesa phenol resin.
 3. The method of claim 1, wherein the adhesive includesan acrylic rubber.
 4. The method of claim 1, wherein the adhesivecomprise a silicon filler at an inclusion by weight value of greaterthan 0% and under about 15% by weight composition ratio.
 5. The methodof claim 1, wherein the adhesive comprises an acrylic rubber at aninclusion by weight value of greater than about 40% and under about 80%by weight composition ratio.
 6. The method of claim 1, wherein theadhesive comprises a phenol resin (such as bisphenol A) and an epoxyresin that is substantially polymerizable to the phenol resin only at areaction temperature substantially greater than room temperature.
 7. Themethod of claim 1, wherein the adhesive comprises an epoxy phenol resinat an inclusion by weight value of greater than 0% and under about 50%by weight composition ratio, a silicon filler at an inclusion by weightvalue of greater than 0% and under about 15% by weight compositionratio, and an acrylic rubber at an inclusion by weight value of greaterthan about 40% and under about 80% by weight composition ratio.
 8. Anelectrophoretic display comprising: an array panel including a thin filmtransistor connected to a gate wire and a source wire, and a pixelelectrode connected to the thin film transistor; an electrophoretic filmincluding an electrophoretic layer and a common electrode; and anadhesive positioned between the electrophoretic film and the arraypanel, wherein the adhesive includes a phenolyic resin such as bisphenolA and an epoxy resin, and wherein the adhesive does not exhibit strongadhesion to at least one of the electrophoretic film and the array panelunless the adhesive is subjected to a curing temperature substantiallygreater than room temperature.
 9. The electrophoretic display of claim8, wherein the adhesive comprises an epoxy phenol resin made of an epoxyresin and a phenol resin and having a weight composition ratio of over0% and under 50%.
 10. The electrophoretic display of claim 8, whereinthe adhesive comprises a silicon filler of over 0% and under 15% byweight composition ratio.
 11. The electrophoretic display of claim 8,wherein the adhesive comprises an acrylic rubber at over 40% and under80% by weight composition ratio.